# Genotype-Dependent Effects of Silicon on Cell Wall Composition and Antioxidant Responses in Oats Under Nitrogen Deficiency

## TL;DR

This study explores how silicon affects oat plants under nitrogen deficiency, showing that silicon improves plant resilience by altering cell wall composition and antioxidant activity.

## Contribution

The study reveals genotype-dependent effects of silicon on cell wall composition and antioxidant responses in oats under nitrogen deficiency.

## Key findings

- Silicon reduced shoot nitrogen content but increased silicon accumulation in both oat genotypes under nitrogen deficiency.
- Silicon decreased lipid peroxidation in both genotypes under nitrogen-deficient conditions.
- Silicon increased cellulose and antioxidant activity in the N-sensitive genotype but reduced lignin and TAL activity in the N-tolerant genotype.

## Abstract

Nitrogen (N) availability strongly regulates plant growth and metabolism, and its deficiency constrains plant development and yield. Silicon (Si) has been reported to enhance plant tolerance to multiple stresses; however, its influence on N metabolism in oats remains poorly understood. This study aimed to investigate the effects of Si on cell wall composition and antioxidant responses in oat genotypes grown under N limitation. Two oat genotypes with contrasting N tolerance were hydroponically cultivated under N-deficient (0.5 mM) or N-sufficient (5 mM) conditions in combination with 0 or 2 mM Si. Growth parameters, N and Si uptake, cell wall structural components, phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) activities, antioxidant responses, and oxidative damage were evaluated. In both genotypes grown under N deficiency, Si supply reduced shoot N content while enhancing Si accumulation. Moreover, Si application decreased lipid peroxidation in both genotypes under N-deficient conditions. In the N-sensitive genotype, Si increased cellulose deposition and antioxidant activity, whereas in the N-tolerant genotype, Si reduced lignin content and TAL activity. We conclude that Si supplementation improves the metabolic performance of oat genotypes under N-deficient conditions by modulating nutrient uptake, antioxidant responses, and cell wall composition.